"static inline" functions are not opaque - as they get inlined into 3rd-party compiled code, we can't change anything they reference, and so the structure layout is still fixed and has to be visible to the user's compiler.

I'm not totally against the changes, but it's worth pointing out that you aren't achieving what the issue title claims, so it's really just code cleanliness (and/or introducing macro-users to static inline functions ;) ).